Self-leveling device



June 22, 1954' w. J. SMITH 2,681,783

SELFLEVELING DEVICE Filed 0st? 18, 1950 2 Shets-Sheet 1 2a 4/ INVENTORJ.

Mum JjWzm U5 BY QWQQM 2 Sheets-Sheet 2 Filed 001;. 18, 1950 I N VEN TOR.[MZQ'gpzJJma't/Z @MQ@M Patented June 22, 1954 UNITED STATES PATENTOFFICE SELF-LEVELING DEVICE William J. Smith, Oregon City, Oreg.

Application October 18, 1950, Serial No. 190,783

4 Claims. 1

This invention pertains to self-leveling devices, and relatesparticularly to the novel construction of a device by which to maintainobjects mounted thereon in a horizontal plane when the device is mountedupon an unstable support.

It is a principal object of the present invention to provide aself-leveling device which is essentially a self-contained unit of butthree cooperating parts which are caused to move freely with relation toeach other in response to forces of gravity.

Another important object of this invention is the provision of aself-leveling device which operates to maintain an object mountedthereon in a horizontal plane but prevents horizontal rotation of theobject.

A further object of this invention is to provide a self-leveling deviceof simplified and therefore economical construction and which issturdily built yet delicately responsive to forces of gravity.

These and other objects and advantages of the present invention willappear from the following detailed description taken in connection withthe accompanying drawings, in which:

Figure l is a perspective view of a self-levelin device embodyingfeatures of this invention, parts thereof being broken away to disclosedetails of construction;

Figure 2 is a sectional view taken through the center of the deviceshown in Figure 1;

Figure 3 is a sectional view taken along the line 3-3 on Figure 2;

Figure 4 is a sectional view of the self-leveling device similar toFigure 3 and showing the same mounted upon a boat;

Figure 5 is a sectional view similar to Figure 2 and showing theself-leveling device in operation upon an angularly disposed support;

Figure 6 is a sectional view similar to Figure 2 showing a modified formof self-leveling device embodying features of this invention; and

Figure 7 is a sectional view showing a still further modified form ofself-leveling device embodying features of this invention, the samebeing shown in tilted position by dotted lines.

Stated briefly, the self-leveling device of the present inventioncomprises a hollow ball, a socket freely overriding the ball, and acounterweight suspended from the socket.

Referring particularly to Figures 1 to 6, inclusive; the self-levelingdevice is shown tocomprise a pedestal-type base I provided with spacedholes 2 for receiving bolts 3 or other fastening means by which the basemay be secured to an unstable support. Examples of the latter mayinclude the deck or other structural member of a boat or airplane.

Mounted upon the central column of the base I is a hollow ball which isformed of the lower semi-spherical section 6 and the upper complementarysegment 5. Section 4 may be secured to the base by any of variousconventional means well-known in the art, such as by the welding 5 shownin Figure 2. Alternatively, the base and section 4 may be formed as anintegral unit, as shown in Figure 6. Section t and segment 5 areprovided with complementary interengaging shoulders I along theirabutting edges, as illustrated, and are there preferably securedtogether detachably by means of set screws 8 for purposes explained indetail hereinafter. Thus, the section 4 and segment 5 cooperate to forma hollow ball which is provided with a circular opening defined by thecircumferential edge 9 disposed diametrically opposite the base I.

A substantially semi-spherical hollow socket Ill is arranged to overridethe hollow ball. In the embodiments illustrated in Figures 1 to 6,inclusive, the inner diameter of the socket is somewhat greater than theouter diameter of the ball in order to provide sufficient spacetherebetween for the ball bearings II and their retainer ring [2. Thediameter of the bearing ring [2 is chosen, in the embodimentsillustrated, so that the bearings are disposed substantially midwaybetween the circumferential edge It of the socket l0 and thecircumferential edge 9 of the ball segment 5, as best shown in Figures 2and 6. In this manner the bearings may roll upon the adjacent surfacesof the segment 5 and socket It within the limits of said edges as theself-leveling device is actuated by movement of the unstable support.

Flexible circular washers l4 and i5 are secured in circumferentialgrooves adjacent the edges 9 and 53, respectively, for sliding contactwith the adjacent surfaces of the socket Ill and segment 5,respectively. These washers function to prevent displacement of thebearing ring it and also to prevent entrance of dirt into the bearingarea. If desired, the washers may be replaced by lugs l6 and I'll, asillustrated in Figure 6. These lugs are disposed at spaced intervalsabout the circumference of segment 5 and project from the outer surfaceof the latter adjacent edge 9 and from the inner surface of the socketit) adjacent edge It, respectively. The lugs function in manner similarto washers l4 and 15 to prevent displacement of the bearing ring 12.

It is to be noted here, with reference to Figures 2 and of the drawings,that by the illustrated use of the single ball bearing ring I2, only theouter surface of the ball segment 5 and the complementary inner surfacearea of the socket IE, i. e., the area disposed between the washers I5and It in Figure 2, need be machined to provide smooth rolling surfacesfor the ball bearings II. However, those skilled in the art willrecognize that various other means and methods may be employed insubstitution for the ball bearing arrangement described hereinbefore topromote maximum freedom of movement between the ball and socket. Onealternative is described hereinafter with reference to Figure 7. Anotheralternative, not illustrated, is to provide a plurality of ball bearingsmounted in circumferential grooves formed in the inner face of thesocket It adjacent the edge I3 and in the outer face of segment 5adjacent the edge 9.

Referring now particularly to Figures 2 and 6 of the drawings, acounterweight I8, preferably of solid construction and of heavy mass,issuspended within the hollow ball by means of a rod I9 secured at itslower end to the counterweight and at its upperend to the socket II]. InFigure 2 the upper end of rod I8 is reduced in diameter and projectsthrough holes provided in the socket It! and a platform 29. The socketand platform are thus secured together by means It is to be observedthat the counterweight is of substantially semi-spherical shape having adiameter slightly smaller than the inner diameter of the hollow ball.The counterweight is installed within theball section 4 before segment 5is attached. The latter'is then mounted upon the section 4 and securedin place by set screws 8. The counterweight may be of any other shapedesired, it being necessary only that it'b'e contained within the ball.The shape and size illustrated is preferred, however, in order toprevent undesirable movemcntof the counter weight within the ball.

In the embodiment illustrated in Figures 1 to 5, inclusive, provision ismade to prevent axial rotation of theplatform 20 relative to the base Iand hence relative to the unstable sup-port upon which the base I ismounted. This provision is afforded by the following means: A pair ofpins 24 are arranged to extend radially outward from diametricallyopposite sides of the counterweight I8. These pins project'along a lineextending through the point which defines the center of rotation of thehollow ball and socket. The pins extend into guide slots 25 which areformed in the inner surfaces of the section It and segment 5. The widthof these slots is substantially equal to the diameter of the pins 24,whereby to receive the latter freely for sliding and pivotal contactwithout permitting excessive lateral displacement of said pins. Theslots'25 extend in a plane normal to the plane of the base I and arearranged atdiametrically' opposite sides of the hollow ball; The lengthof slots 25' is determined by the maximum angle through which the deviceis to operate effectively to maintain the platform 28 upon a horizontalplane. In the illustration, the device is constructed to operateeffectively through approximately 88, i. e. to maintain the platform ina horizontal plane during tilting of the base I to approximately 44 inany direction from a vertical line. Accordingly, the arcuate length ofslots 25 shown in the drawing is at least 88, measured radially from thecenter of the hollow ball;

It will be apparent to those skilled in the art that the effectivemaximum angle of operation of thepresent device is also determined bythe size of the opening in the ball defined by the circumferential edge9. Thus, in the foregoing illustration, the diameter of said opening isgreater than about 88 by the diameter of the sup-porting rod I9.

The device illustrated in Figures 1 to 5, inclusive, operates tomaintain the platform 28 ina horizontal plane" and to prevent horizontalrotation of the platform, as follows? Let it be assumed that the base Iis tilted in the plane of the drawings from the position shown in Figure2 to the position shown in Figure 5. During this tilting of the base,the pins 2 merely slide along the guide slots 25 because the latter aredisposed in the same plane in which the base .I is being moved. Let itnow be assumed that the'base I is tilted in a plane perpendicular to theplane of the drawing from either of the positions shown in Figures 2 and5. During such tilting the pins'fi. pivot axially within the guide"slots 25 because said pins are positioned in line with the center ofrotation of the hollow ball and the socket Ii). Thus, it is" appareritthat the tilting of base I in any direction within the limits defined bythe opening in the hollow ball and by the length of slots 25 may beaccommodated by the simultaneous axial rotation and longitudinalmovement of pins 24 within the guide slots 25.

The interengagement of the pins and slots operates additionally 'to'prevent horizontal rotation of the platform 20-; This" feature affordsparticular utility of the device aboard a ship or boat for mounting acompass upon the platform 29. Referring toFigure 4 of the drawings, thecooperating guide slots 25 and pins 24' permit the boat 26' to roll andpitch in any direction without disturbing the horizontal position of a'compass mounted upon the platform 29. The slots and pins preventhorizontal rotation of the platform, however, and thus the compass ismaintained in its required position relative to the longitudinal centerline 2? of the boat. It will be understood that the pins 24' need not bearranged in line with the center line 21, as

shown, but may be disposed in any other position desired. It ispreferred, in any case, to position the pins '24 and slot '25 in theline of direction in which abrupt movements of the unstable sup portmost frequently occur. In this manner the shearing strains exerted uponthe pins 24 are reduced to 'a' minimum. 7

The'modii'ication'illustrated in Figure 6 of the drawing differs ingeneral construction from the device of Figures 1-5, inclusive, in theabsence of the pins 2 5 and guide slots 25. Incidental differ encesreside in the manner of detachably mount ing the platform 20, asexplained hereinbefore. and in the shape of the counterweight I8. In thelatter instance, the counterweight comprises a substantially greaterportion of asphere than does the counterweight previously described; The

shapes illustrated are merely suggestive of several, it being understoodthat the counterweight may comprise a complete sphere if desired.

The device shown in Figure 6 not only provides for the maintenance ofthe platform in a horizontal plane during movement of the base I, butalso permits horizontal rotation of the platform. This latter motion ispermitted because rotation of the counterweight about a vertical axis isnot restricted by the pins 24 and registering slots 25 provided in thestructure previously described. This feature affords utility of thedevice for various purposes such, for example, as a mounting for a deckchair, whereby to maintain the chair level during motion of the boat andalso to permit the chair to swivel in a horizontal plane. On the otherhand, if it is desired to restrict horizontal rotation of the chair, thedevice shown in Figures 1-5 of the drawings may be employed.

The modification shown in Figure 7 of the drawings differs primarilyfrom the structures described hereinbefore in the arrangement of thecounterweight. The device comprises a hollow spherical ball which isopen at both upper and lower ends. The ball is mounted upon an enlargedcylindrical housing 3|, with the lower opening of the ball registeringwith a hole 32 provided in the housing. The ball is secured in place bysuch means as bolts 33 extending through the out-turned flange 34defining the periphery of the lower opening of the ball. The housing 3iis in turn secured to a base 35 by means of bolts 36.

A substantially semi-spherical socket 31 having an inner diametersubstantially equal to the outer diameter of the hollow ball 30 isarranged over the upper opening of the ball for sliding contact with thelatter. The contacting surfaces of the ball and socket may be greased orotherwise treated to reduce friction and promote freedom of motion.Grease seals 38 and 39 may be provided adjacent the upper opening of theball 38 and the circumferential edge of the socket 31, respectively, toretain the grease therebetween. Alternatively, the anti-friction ballbearing arrangment described hereinbefore may be employed if desired.

The socket 31 supports a platform 40 which is secured thereto by meansof the nut 4| which is threaded onto the upper end of rod 42. This rodis secured to the socket 31 and depends therefrom through the hollowball 30 and into the housing 3|. A counterweight 43 of substantial sizeand weight is mounted upon the lower end of rod 42. Thus, thecounterweight is displaced a greater distance from the center 44 of thehollow ball than are the counterweights of the structures describedhereinbefore. This latter construction is used to advantage forsupporting objects of considerably greater weight upon the platform 40than can be supported effectively upon the platform 20 of the previouslydescribed devices.

In order to prevent horizontal rotation of the platform 40 with respectto the housing 3 l means similar to the pins 24 and guide slots 25previously described may be provided, as follows: An arm 45 is securedto rod 42 at the center 44 of the hollow ball 33. The arm extendsperpendicularly to rod 42 and terminates at its ends adjacent the innersurface of the ball 33. Pins 46 are provided on the opposite ends of thearm 45 and they extend into the guide slots 41 formed at diametricallyopposite sides of the hollow ball 30. The slots extend in a plane normalto the plane of base 35, in manner similar to slots 6 25 describedhereinbefore. The length of slots 4! and the openings in the hollow ball30 determine the angle through which the device will operate to maintainthe platform 40 in a horizontal plane, as previously described.

It is to be understood that the arm 45, pins 45 and slots 41 need not beprovided if restriction of horizontal rotation of the platform 40 is notdesired. By elimination of these elements, the device operates in themanner of the device illustrated in Figure 6.

A ring of rubber 48 or other resilient material is preferably secured tothe inner surface of the housing 3| in proper position for engaging thecounterweight 43 when the housing is tilted to its maximum limits, asillustrated in dotted lines in Figure '7. This ring forms a cushion toabsorb the shock of impact of the counterweight, whereby to decrease thesound of impact and to prevent damage to the housing.

It will be apparent to those skilled in the art that the ball 30 may bemounted directly upon an elevated base without the necessity of housing3|, in which case the flange 34 constitutes a base for the device. Forexample, the ball may be secured to a floor and the rod andcounterweight suspended below the floor to any distance. This may bedesirable when a large object such as a table or bed is to be supportedupon the socket 31.

It will be further apparent to those skilled in the art that variouschanges may be made in the structural details described hereinbefore andillustrated in the drawings without departing from the scope and spiritof the present invention. For example, the pins 24 or 45 may be formedas integral parts of the counterweight l8 or arm 45, respectively. Ineither case a ring of ball or roller bearings may be mounted upon thepins, if desired, to promote freedom of movement of the latter.Alternatively, each of the pins may comprise a roller or ball bearingmounted for rotation in a bracket or other support provided at theproper positions previously described.

'It will be apparent that the pins 24 may alternatively be secured toand project radially from diametrically opposite sides of the innersurface of socket ID to engage guide slots formed in the outer surfaceof the ball sections 4 and 5. The illustrated arrangement is preferred,however, because the parts are enclosed within the ball. In any case thepins function with the cooperating slots to interengage the ball andsocket at points extending through the center of rotation of said balland socket in such manner as to prevent relative rotation of said partsabout a vertical axis.

These and other modifications may be made as desired. Accordingly, theforegoing description is intended merely as exemplifying andillustrating the features of the invention and is not to be consideredin a limiting sense.

Having now described my invention and the manner in which the same maybe used, what I claim as new and desire to secure by Letters Patent is:

1. A self-leveling device comprising, in c0mbination, a hollow ballhaving an enlarged opening therein, a base connected to the ballopposite said opening, a hollow socket overlying the ball for movementrelative thereto, a counterweight suspended freely from the socket, saidball having guide means formed at diametrically opposite sides andextending in one plane only normal to the plane of the base, pin meansmounted in fixed relation to the socket and projecting in diametricallyopposite directions along one line only extending through the center ofrotation of the ball and socket, said pin means slidably engaging theguide means for movement longitudinally along and for rotation axiallywith respect to the guide means, and means on the socket for mounting anobject to be supported.

2. A self-leveling device comprising, in combination, a hollow hallhaving anenlarged opening therein, a base connected to theballoppositesaid opening, a hollow socket overlying the ball for movementrelative thereto, a counterweight suspended freely from the socket andcontained within the hollow ball, said ball having guide means extendingin one plane only normal to the plane of the base, pin means mounted infixed relation to the socket and projecting along one line onlyextending through the center of rota-- tion of the hall and socket, saidpin means slidably engaging the guide means for movement longitudinallyalong and for rotation axially with respect to the guide means, andmeans on the socket for mounting an object to'be supported.

3. A self-leveling device comprising, in combination, a supported hollowball having an enlarged opening therein, a hollow socket overlying theball for movement relative thereto, the ball and socket having a commoncenter of rotation, a counterweight suspended from the socket, in:terengaging pin and guide means disposed in fixed relation to the balland socket, the guide means extending radially about the said commoncenter of rotation in onevertical plane only, the pin means projectingalong one line only extending through said common center of rotation and8, slidably engaging the guide means, whereby the pin means may movelongitudinally along'and-rotate axially with respect to the guide means.

4. A self-leveling device for supporting an article, comprising asupported hollow ball havingv an. enlarged top opening therein, guidemeans within the ball extending radially about the center of the ball inone vertical plane only, transverse support means within the ball, pinmeans on the ends of the transverse support means and projecting alongone line only extending through the center of the ball and slidablyengagingthe guide means, whereby the pin means may move longitudinallyalong androtate axially with respect to the guide meanavertical supportmeans secured to the transverse support means and extending upwardlytherefrom-through the opening in the ball for supporting an article, andcounterweight means extending downwardly from the transverse supportmeans below the line axis of the pin means.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,168,727 Jenigar Jan. 18, 1916 1,260,181 Garnero Mar. 19,1918 1,365,233 Earle Jan. 11, 1921' 1,569,325 Leib Jan. 12, 1926 1,623,l27' Manrock Apr. 5, I92

FOREIGN PATENTS Number Country Date 11,227 Great'Britain of 1891 387,530France of 1 908

